Why we always recommend a combined system. Modern thieves don't just steal keys. Relay attacks, CAN bus injection, key cloning and OBD hacking mean your vehicle can be taken without any physical break-in. An immobiliser blocks these digital theft methods and stops the vehicle starting in the first place. A tracker alone only helps after the vehicle is already gone. A combined system does both - it defeats modern theft methods and gives you the best chance of recovery if the worst still happens.